Regression: incorrect line numbers in debug info since 4.5+

Hello,

I found out while single stepping a new template function in gdb that 
gcc generates bad/inaccurate line numbers in the debug info. 
Optimization was turned off, but the execution jumped strangely, see 
below. gcc-4.4 and the current clang produced the expected results, gcc 
4.5, 4.6, 4.7, 4.8 all had problems. The code was factored out from a 
proof-of-concept hack.

Here is the trace that was produced in gdb by single stepping the 
program with 'n'. The program was compiled w/ gcc 4.8.0 git commit e7ae865c:

COLLECT_GCC=gcc-4.8.0
COLLECT_LTO_WRAPPER=/home/usr-local/bin/../libexec/gcc/x86_64-unknown-linux-gnu/4.8.0/lto-wrapper
Target: x86_64-unknown-linux-gnu
Configured with: ./configure --enable-languages=c,c++ 
--program-suffix=-4.8.0
Thread model: posix
gcc version 4.8.0 20120605 (experimental) (GCC)

g++-4.8.0 -g -O0 -Wall -Wextra -o dbginfobug.o -c dbginfobug.cpp
g++-4.8.0 -g -o dbginfobug dbginfobug.o

11              while (C c = *f++) {
12                      if (c == '$') {
56                              if (o < e) {
57                                      *o = c;
59                              ++o;
// the first anomaly: the line printed is AFTER the loop, while we're 
still in the loop